Coiled-filament non-woven fabrics

ABSTRACT

AN ELASTIC NON-WOVEN FABRIC WITH HIGH MULTIDIRECTIONAL STRETCHABILITY, HAVING TRASVERSELY INTERSECTING WRAPS AND FILLINGS COMPOSED OF RESILENT HIGHLY EXTENSIBLE COIL STRANDS OF MONO-FILAMENTARY NATURE. THE FABRIC IS MADE BY FORMING A FIRST SINGLE LAYER STRUCTURE OF PARALLEL COIL STRANDS, FORMING A SECOND SINGLE LAYER STRUCTURE OF PARALLEL COIL STRANDS WHICH OVERLIE AND CROSS THE STRANDS OF THE FIRST LAYER, AND COMPACTING THE TWO COIL LAYERS INTO ONE ANOTHER SO THAT THE COIL STRANDS OF EACH GROUP ARE ENTANGLED WITH THE CROSSING COIL STRANDS OF THE OTHER GROUP FROM ONE SIDE ONLY AND ARE INTERCONNECTED SO AS TO BECOME A COHESIVE STRUCTURE IN WHICH THE AXES OF ALL THE COIL STRANDS ARE IN A SINGLE COMMON PLANE.

Feb. 9, 1971 R. N. STEEL 3,562,079

COlLED-FILAMEN'I. NON-WOVEN FABRICS Filed 001:. 27. 1967 2 Sheets-Sheet 1 ATTOP YO Feb. 9, 1971 R STEEL 3,562,079

COlLED-FILAMENT NON-WOVEN FABRICS I T i Filed Oct. 27. 1967 2 Sheets-Sheet 2 nlllllllH mmml .II lILHQHOHO X v 1 INVENTOR. 1 D Foyer/Y S7554 -WW/M&L

United States Patent 0 3,562,079 COILED-FILAMENT NON-WOVEN FABRICS Robert N. Steel, South Bend, Ind, assignor to Uniroyal, Inc., New York, N.Y., a corporation of New Jersey Filed Oct. 27, 1967, Ser. No. 678,751 Int. Cl. D0411 3/07, 13/00 US. Cl. 161-47 26 Claims ABSTRACT OF THE DISCLOSURE An elastic non-woven fabric with high multidirectional stretchability, having transversely intersecting warps and fillings composed of resilient highly extensible coil strands of mono-filamentary nature. The fabric is made by form ing a first single layer structure of parallel coil strands, forming a second single layer structure of parallel coil strands which overlie and cross the strands of the first layer, and compacting the two coil layers into one another so that the coil strands of each group are entangled with the crossing coil strands of the other group from one side only and are interconnected so as to become a cohesive structure in which the axes of all the coil strands are in a single common plane.

The foregoing abstract is not to be taken either as a complete exposition or as a limitation of the present invention, and in order to understand the full nature and extent of the technical disclosure of this application. reference must be had to the following detailed description and the accompanying drawings as well as to the claims.

BACKGROUND OF THE INVENTION This invention relates to a novel class of non-woven fabrics.

Non-woven fabrics of one presently known class are generally made of masses of randomly oriented continuous filaments or staple fibers (or both) arranged into web form. Depending on the nature of the filamentary material, and in certain cases also on the type of process by which the web is formed, such web may be additionally treated, e.g. either mechanically such as by needling or padding, or adhesively such as by application of a suitable binder, or by application of heat and/or pressure, to retain the fibers or filaments in a coherent mass. Nonwoven fabrics of another known class are generally constituted by superposed layers of transversely oriented parallel filaments or threads which are bonded to one another at their points of intersection by adhesive means or by heat and pressure induced fusion. Non-woven fabrics of any of these are usually non-elastic, and even if they can be stretched either longitudinally or transversely or in both directions, their maximum stretchability is relatively minimal and they do not return to their original dimensions. Moreover, if it is desired to produce relatively thick non-woven fabrics of any of these types, it is necessary to employ appropriately larger masses of fibers or multiple layers of the basic web formation, which makes the final fabric more difficult and costly to produce.

SUMMARY OF THE INVENTION It is an important object of the present invention to provide a novel type of non-woven fabric which is highly elastic and stretchable in all directions in the plane thereof, which at the same time is highly flexible yet possessed of considerable resistance to compression in a direction transverse to the plane of the fabric, and which can be produced as a single-layer structure for all practical thickness values thereof.

It is another object of the present invention to provide such non-woven fabrics, as well as processes of making the same, which enable the hereinbefore outlined drawbacks and disadvantages of the known types of non-woven fabrics and their methods of manufacture to be avoided.

Generally speaking, a non-woven fabric according to the present invention is composed of two sets of highly resilient spring-like mono-filamentary coil strands (these terms will be more fully defined hereinafter), the coils in each set having their axes parallel to one another and perpendicular to the axes of the other set of coils, and the two sets of coils being compacted from two parallel plane structures into a uniplanar or single-layer threedimensional structure the thickness of which is determined by the widths or cross-sectional dimensions of the coil turns. In essence, the arrangement resembles a grid line or checkerboard pattern of entangled coil springs. Where the coils are initially stretched prior to the compaction, their retraction upon release of the stretching forces after the compaction causes them to become mechanically locked to each other at their regions of intersection. If desired, the fabric so produced may in addition be treated with a suitable binder capable of either physically tying or adhesively bonding the various coils to one another at their points of intersection as well. On the other hand, where the coils are compacted without being first stretched, with the result that they lie more or less loosely one within the other, then the application of such a binder to the points of intersection or, if the nature of the coil strand material permits, a fusion of the strands at such points of intersection, would be required. Where desirable for coil protection purposes, a sufficient quantity of the binder" material may be applied to the fabric so as to ensure an adequate coating on the entire surfaces of the various coil strands.

By virtue of the construction according to the present invention, wherein the spring-like, highly extensible and resilient coil strands of which the fabric is made extend both warpwise and weftwise of the fabric, the same is rendered elastically stretchable in all directions in the plane of the fabric, i.e. the plane containing the axes of the coils, while the disposition of the turns of the coil strands in planes substantially perpendicular to the plane of the fabric imparts to the latter high flexibility and a relatively high resistance to compression. Further, since the coils can be shaped to have any desired effective diameter, the making of the fabric with any given thickness requires only the use of coils of an appropriate crosssectional dimension, and to make a fabric of any relatively great thickness it is generally not necessary (although practical considerations may make it desirable at times) to superpose on and bond to one another a plurality of fabric plies of lesser thicknesses.

For the practice of the present invention, one class of materials of which the coil strands generally may be made can be denoted as rigid and semi-rigid, including filaments of glass, metal wire, polyvinyl chloride and other vinyl resins, nylon, polyester, polyethylene, polypropylene, isotactic polystyrene, polycarbonate, acrylic resin, acrylonitrile-butadiene-styrene (ABS) resin, cellulose acetate and other organic acid esters and ethers of cellulose, and the like. Another class of suitable materials can be denoted as soft and resilient, including Spandex polyurethane thread, uncured latex and cut rubber threads, filaments of plasticized polyvinyl chloride, and the like. It is within the contemplation of the present invention, however, that such coil strands can also be made of such materials as cotton or rayon threads, paper yarns or threads, and the like, suitably impregnated, preferably prior to the coil-forming operation, with such materials as heat-curable or room temperature vulcanizing thermosetting polyester and epoxy resins, hot melts of thermoplastic resins, vinyl latices, urethane latices, natural and synthetic rubber latices, and the like. Particular methods of forming coil strands of the various materials will be more explicitly set forth hereinafter.

The binders which may be employed in the practice of this invention are preferably of such a nature as to act as an adhesive for bonding the coil strands to each other at their cross-over points. It is contemplated within the ambit of the present invention, however, that the binders may only encapsulate the coil strands at the cross-over points so as to tie or bind them together in the mechanical or physical sense. Materials which are found well suited for these purposes are dispersions of plastics and rubbers such as vinyl chloride latices, acrylic latices, natural and synthetic rubber latices, urethane latices, plastisols, organosols, etc., and solutions of rubbers and plastics, including solutions of elastomers such as buna-N and neoprene rubbers, and solutions of plastics such as polyvinyl chloride, polyurethanes, vinylidene chloride, etc.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects, characteristics and advantages of the present invention will be more fully understood from the following detailed description thereof when read in conjunction wlth the accompanying drawings, in which:

FIG. 1 is a partly schematic plan view of a nonwoven fabric according to the present invention;

FIG. 1a is a similar plan view, on an enlarged scale, of a portion of the fabric shown in FIG. 1;

FIG. 2 is a sectional view taken long the line 22 in FIG. 1a and drawn on a still more enlarged scale;

FIGS. 3, 4 and 5 are perspective illustrations of differently shaped coil strands constituting the basic structural elements used in the practice of the present invention;

FIG. 6 is a top plan view of a device which may be used in the manufacture of the fabric according to the present invention and illustrates the first stage of the production of the fabric;

FIG. 7 is a fragmentary, perspective view of the device and illustrates the preliminary arrangement of the coils in the second stage of the production of the fabric according to the present invention;

FIG. 8 is a fragmentary sectional view taken along the line 8-8 in FIG. 7;

FIG. 9 is a view similar to FIG. 8 and illustrates the post-compaction arrangement of the coil assembly; and

FIG. 10 is a diagrammatic illustration of one manner of applying a binder to the finished fabric constituted by the compacted coil assembly of FIG. 9.

PREFERRED EMBODIMENTS Referring now to the drawings in greater detail, the basic structural unit of the non-woven fabric (FIGS. 1, la and 2) according to the present invention is an elongated coil strand made of any suitable material of the types hereinbefore set forth. Merely by way of example, such a coil strand may be of circular cross-section as indicated at 21 in FIG. 3, or of oval cross-section as indicated at 21a in FIG. 4, or of polygonal cross-section, e.g. square as indicated at 21b in FIG. 5. These coil strands are shown each with its turns lying closely adjacent one another, but obviously each may have its turns relatively spaced from one another, depending on the elongation characteristics desired for the coil, as will presently become clear.

Each strand 21, 21a, or 21b is made u of a single mono-filament of the material involved, it being understood, however, that the term mono-filament is here used in a sense somewhat broader than is usually the case. Thus, this term is intended to designate not only conventional extruded or cut mono-filaments, but also unitary strands formed by treating, through fusion, co-

agulation, impregnation, twisting, braiding or the like, yarns or threads composed of either bundles of continuous filaments or of spun staple fibers so as to make them into cohesive structures.

In general, there is one basic method of forming any of the coil strands 21, 21a and 21b irrespective of the nature of the material of which it is made, although it will be appreciated that the nature of any given one of the various materials may require a respective modificat10n of the basic procedure. Thus, where the strand is formed from glass fiber, the molten glass is drawn into the form of a filament of the desired thickness from an or1fice of appropriate diameter in conventional manner (or a plurality of thinner filaments are coagulated into a umtary structure), and the resultant mono-filament thereafter, while still in a hot and pliable state, is wound onto a rotating rod of the required cross-sectional shape and size on which it is permitted to set by cooling. Where the mono-filament is a single-strand metallic wire, the wire is cold drawn and wrapped about a mandrel of suitable shape and size (this size generally will be somewhat smaller than the desired final cross-sectional dimensions of the coil to compensate for the inherent springiness of most metals and metal alloys which will be found suited for use in the field of the present invention, e.g. carbon steel, iron, beryllium, aluminum, stainless steel, copper, high electrical resistance alloys, etc.). The mono-filament may, of course, also be a multi-strand wire, e.g. a twisted or braided wire, and may be bare or coated with any desired material, such as vinyl or polyethylene insulatron, etc.

On the other hand, when a mono-filament of a thermoplastic material is used, it is wound onto a suitably shaped and dimensioned rod or mandrel (which may be rotated during the winding operation) and, while in that state,

is exposed for a predetermined time interval to a relatively elevated temperature, for example in a hot air oven, whereby the filament becomes heat-set in its coiled form. It will be understood that if such a filament is wound onto the mandrel immediately after extrusion and while still hot, it would probably not be necessary to post-heat the filament specially in order to set it in its coiled form. When the filament is made of uncured latex or cut rubber thread, the same (the composition of which will contain a suitable curing or cross-linking agent) is Wound 1n its uncured state onto a mandrel of the desired size and the entire assembly is then subjected to the necessary thermal and/ or radiation conditions to cause the compo- SllLlOIl to cure and permit the filament to become set in its coiled shape. Where the mono-filament is to be made of thread or yarn of such materials as cotton, rayon, paper and the like, the thread or yarn, having first been impregnated either with a heat-curable or room temperature vulcanizing thermosetting polyester or epoxy resin, or possibly with a rubber or plastic latex or with a hot melt of a thermoplastic material such as polyvinyl chloride, a polyamide resin, cellulose acetate butyrate resin, and the like, 18 wound onto a mandrel and then exposed to the proper thermal cycles, for example heating in the case of the heat-curable thermosetting resin impregnants or cooling in the case of the hot melt thermoplastic impregnants, whereby it becomes set in its coiled shape.

As a practical matter, the mono-filament of which the basic coil strand is made may have any suitable denier, and the diameter or thickness of the mono-filament is not limited to any particular range of values, since a particular choice of filament diameter or thickness will generally depend on a combination of factors or parameters such as the desired cross-sectional dimensions of the coil, the strength of the material of which the filament is made, the loads and stresses to which the coil strand ultimately will be subjected in use, etc. For the same reasons, as well as for the hereinbefore indicated reason that the coil cross-sectional dimension determines the thickness of the fabric, the coils may also have any cross-sectional dimension which is found desirable or necessary.

For the purpose of making a non-Woven fabric 20 of the type shown in FIGS. 1 to 4, the method illustrated by FIGS. 6 to 10 has been found to be at the present the best mode of achieving the desired result. Merely by way of example, the following description will be in terms of the use of coil strands of helical configuration of the type illustrated at 21 in FIG. 3, i.e. having a circular cross-section of uniform diameter along the entire axial length of each strand, but it will be apparent that the same principles would apply to coil strands of oval or polygonal cross-section as well.

More particularly, in accordance with the most basic aspects of this method, the fabric may be produced with the aid of a preferably square or rectangular, generally tenter-like, frame 22 provided with two perpendicular sets of parallel rows of upstanding pins or pegs 23 and 24. Quite obviously, the frame may be either of a fixed size or constructed of separable sections adapted to have suitable pin-equipped removable inserts interposed therebetween. Alternatively, an associated pair of elongated bars designed to constitute two opposite sides of such a frame may be provided with aligned recesses or other attachment means to which suitable cross-bars designed to constitute the other sides of the frame may be releasably secured. It will be equally apparent that the sides of the frame and the opposed rows of pins need not necessarily be parallel to one another and that one or more of them may even be curved, thereby to enable non-square or non-rectangular fabric sections to be produced.

In the first stage of the production of such a fabric 20, a plurality of the coil strands 21 having either closely positioned turns as shown in FIG. 3 or more widely spaced turns, are laid across the frame 22, as indicated at 21' in FIGS. 6 and 7, and secured at their opposite ends in side by side relation to the oppositely disposed pairs of pins or pegs 23. The size of the frame may be such that the coil strands 21' will be stretched between about 0 and 900% of their original length. In the lower limiting case. therefore, the coils will be unstretched, but for reasons which will become clear as the description proceeds, in that event the turns of each coil strand will have to be spaced from one another. Above the lower limiting case, stretching the coil strands to between about 300 and 500% of their original relaxed state lengths is found to be preferred.

After a complete layer of coil strands 21 has been thus formed on the frame, a second set of unstretched or stretched coil strands 21, designated by reference numeral 21" in FIGS. 7 and 8 (wherein stretched coils are shown), is laid across the frame 22 over the first layer and secured in side by side relation to the oppositely located pairs of pins 24 in a direction perpendicular to the direction of the strands 21'. The so-formed second layer is then pressed against and compacted with the other one, causing the two sets of coil strands to be entangled and jointly disposed essentially in a common plane, i.e. with the locations of the fabric surface-defining zeniths and nadirs of the sets of coils being in respective common planes which are parallel to one another and to the common plane of the axes of the various coil strands. This is the condition illustrated in FIG. 9. It should be understood that within the purview of the present invention only one of the coil strand layers may be stretched while the other is unstretched.

In the case where one or both of the sets of coil strands are stretched, the entire coil strand assembly can now be removed from the frame, whereupon it will contract in one or both of the two transverse directions, due to the resiliency of the stretched coil strands, but only to a limited extent, leaving the final fabric dimensions greater than the pre-assembly relaxed state axial lengths of the various coil strands in the direction of the stretched strands, preferably ranging from about 50 to of the stretched lengths of the respective coil strands, As a result of the contraction, furthermore, the crossing coil strands will also be mechanically interlocked with one another as shown in FIG. 9, even if only one set of coils contracts.

It will be understood that for many purposes and end uses, generally those of a static nature which entail no undue stresses and strains, the so-formed fabric, with the coil strands only mechanically interlocked, will have adequate strength and resistance to separation and require no after-treatment to enhance the cohesion of the strands. Where the fabric in use will be subjected to considerable dynamic stresses and strains, however, in particular flexure, it is found advisable to subject the fabric to a further coil-connecting treatment so as to cause the two sets of coil strands to be either mechanically tied or bonded to one another at their points of intersection or cross-over points. Such a treatment, for example, may be an application of localized heating to fuse or bond the crossing strands to one another where they cross and are in contact, assuming that the nature of the material of which the strands are made admits of such a result.

According to the preferred aspects of the present invention, however, the treatment may be the application of a binder (as hereinbefore defined) to the fabric to effect either a mechanical tying or an adhesive bonding of the crossing strands to one another where they cross or are in contact. One example of a binder application method is diagrammatically illustrated in FIG. 10 which shows the fabric 20 immersed in a bath 25 of such a binder, and although the fabric is shown as being immersed after being removed from the frame 22, it may just as well be so treated while still on the frame. Alternatively, the binder can be applied to the fabric, preferably while the latter is still on the frame, either by means of applicator rollers or by means of spraying devices. Thereafter, depending on the type of binder employed, the treated fabric will then have to be subjected to a final treatment, usually either a heating or a cooling operation, to dry and/ or fuse the binder. Where the latter is a room temperature curing material. of course, external heating or cooling will generally not be required and the final treatment will consist merely of exposing the fabric to room temperature for a sufficient time interval to permit the binder to cure and set.

In the case where the coil strands are not stretched when laid onto the frame 22, one variation from the foregoing procedure which arises is that the application of a binder or a fusion treatment becomes essential to avoid the possibility that the coils, not being mechanically interlocked, could come apart during use of the fabric. Moreover, practical considerations based on the same possibility dictate that the application of the binder should also be made while the coil strand assembly is still on the frame (even though in theory the loose coil strand assembly could conceivably be lifted off the frame prior to the binder application).

Generally, and irrespective of whether streteched or unstreteched coil strands are used, the amount of binder applied will only be such as to satisfy the bonding or tying requirements, e.g. after an immersion treatment, the excess will be drained off before it dries, leaving only the part trapped at the cross-over points of the coils, as at 26 in FIG. 2. As previously indicated, however, if found desirable for coil protection purposes, a sufficient amount of binder may be employed not only to effect the bonding or tying of the coils to each other but also to adequately coat the entire surface of each coil strand.

It will further be understood that there is by and large no unique relationship which must be maintained between the parameters of coil diameter or cross-section and spacing of the pins on the frame 22 other than that such spacing must be sufficient (a) to accommodate the parallel coils in non-interfering side by side relation during the assembly operation and (b) to ensure that even after removal of the fabric from the frame, especially if the fabric contracts, the coils arrangement is loose or open enough. to afford unhampered flexibility. Obviously, the axial length of each coil strand as produced may initially be very great, in which case, after removal from the mandrel, it can be cut into shorter lengths as desired, or a large number of relatively short coil strands of the desired axial lengths can be formed in the first instance.

The following examples will serve further to illustrate the present invention.

EXAMPLE I Nylon mono-filament having a diameter of 0.012 inch is tightly wrapped in a series of successive contacting winds onto a /8 inch diameter steel rod or mandrel. The latter, with the filament still wound thereon, is then exposed to a temperature of about 365-378 F in a hot air oven for 20 minutes, to heat set the nylon filament in coil form.

192 such coil strands each 7 inches long are mounted on a square frame open in the center and having a plurality of upstanding pins extending from its upper surface, the pins on each side of the frame being spaced about inch apart and being aligned with a corresponding set of pins on the opposite side, and the parallel rows of pins being 28 inches apart. In the mounting stage, the nylon coil strands are stretched by approximately 300% of their original length, and each stretched coil strand is hooked at its opposite ends to a respective pair of opposed and aligned pins. After a first layer of 96 such coil strands has been formed, a second layer of stretched coil strands is formed from the remaining 96 coil strands oriented transversely to the first ones and hooked to the opposed and aligned pins on the other two sides of the frame. The two layers are then forced against and compacted with each other, causing the coil strands of each set to become entangled with the perpendicular coil strands of the other set, until the entire assembly is transformed into an essentially uniplanar structure.

While still on the frame, the so-formed coil strand assembly is roller-coated on both faces with a solution of a thermoplastic polyurethane (e.g. a non-curing polyurethane made by reacting 1 mole of polytetramethylene glycol, molecular weight 1000, 2 moles of p,p'-diphenylmethane diisocyanate, and 1 mole of butanediol, and available commercially under the trademark Roylar E8) in tetrahydrofuran. The frame is then placed into a drying oven to remove the solvent, the drying temperature being below the heat setting temperature for the nylon filament and generally between about 70 and 150 F. After this stage is completed, the assembly is removed from the frame, whereupon it contracts to yield a mechanically interlocked and adhesively bonded non-woven fabric, such as shown in FIGS. 1, 1a and 2, having transverse dimensions of about 18 x 18 inches, i.e. about 64% of the lengths of the respective stretched coil strands.

EXAMPLE II Polypropylene mono-filament having a diameter of 0.012 inch is coiled in the manner set forth for nylon in Example I, except that while wound on the mandrel it is subjected to a heat setting temperature of 320 F. for 30 minutes. 7-inch lengths of the so-formed coil strands are then stretched to 28 inches in length and fastened at their opposite ends in two layers to paired and aligned pins, as previously described, on opposed sides of a square frame of appropriate dimensions. The two layers of perpendicular coil strands are then pressed against and compacted with each other to produce the non-wovenfabric which, upon removal from the frame, contracts to approximately 18 x 18 inches in size.

EXAMPLE III A non-woven fabric is made of polypropylene monofilament in the same manner and with the same equipment as described in Example II, except that prior to being released from the frame, the fabric is first impregnated by means of an immersion treatment with a 5% solution of a thermoplastic polyurethane in tetrahydrofuran and then permitted to dry by solvent evaporation. After removal from the frame, the fabric contracts to about the same size as that of Example II.

The non-woven fabrics of the present invention may be utilized in a variety of applications, e.g. as shock absorption materials, filter materials, extensible bag materials, lightweight rug underlay, upholstery fabric, reinforcing fabric for extremely thin, weak films of paper, etc. Especially when made of suitable high resistance wire, such a fabric may be used as an electric heating element for various structures. The intended use of such a fabric for and in any given environment or application may, of course, entail the use of coil strands of non-circular crosssection, for example where different compressibility characteristics than those provided by circular cross-section coils are required. By the same token, for example Where a desire to achieve special effects so dictates, different types of mono-filament coil strands may be incorporated in any given fabric according to this invention. Thus, one layer structure may be composed of coil strands of one material, while the other layer is composed of coil strands of a different material, or any one or more layers may be composed of mixtures of coil strands of different materials. Other variations will readily suggest themselves to those skilled in the art.

It is to be understood that the foregoing disclosure of preferred embodiments of the present invention is for purposes of illustration only, and that the various structural and operational features and relationships described herein may be modified and changed in a number of ways none of which entails any departure from the spirit and scope of the present invention as defined in the hereto appended claims.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. An elastic non-woven fabric with high multi-directional stretchability, comprising a cohesive structure composed of two groups of resilient and highly extensible coil strands of mono-filamentary nature, all coil strands of each group crossing those of the other and being laid into and entangled therewith from one side only, and the axes of all said coil strands being disposed in a single common plane.

2. A non-woven fabric according to claim 1, said groups of coil strands being laid one into the other while in their relaxed and unstretched states, and the crossing coil strands being connected to one another by means of a binder at their points of intersection 0t render the structure cohesive.

3. A non-woven fabric according to claim, the monofilarnent constituting at least some of said coil strands being made of a material selected from the group consisting of fibers of natural and synthetic rubber and synthetic plastic materials.

4. A non-woven fabric according to claim 1, the monofilament constituting at least some of said coil strands being made of glass fiber.

5'. A non-Woven fabric according to claim 1, the monofilament constituting at least some of said coil strands being made of metal wire.

6. A non-woven fabric according to claim 1, the monofilament constituting at least some of said coil strands being made of'a material selected from the group consisting of threads and yarns of fibrous material impregnated with a material selected from the group consisting 0 natural and synthetic rubbers and resins.

7. A non-woven fabric according to claim 1, the two groups of coil strands being mechanically interlocked, by virtue of a contraction of said coil strands of at least one of said groups from a stretched state imparted thereto prior to and during the laying thereof into the coil strands of the other group, to render the structure cohesive.

8. A non-woven fabric according to claim 7, the crossing entangled coil strands further being connected to one another by means of a binder at their points of intersection.

9. A non-woven fabric according to claim 8, said coil strands being coated by said binder over the entire remainder of their surfaces.

10. A non-woven fabric according to claim 1, the axes of the crossing entangled coil strands being straight and perpendicular to one another.

11. A non-woven fabric according to claim 10, said groups of coil strands being laid one into the other While in their relaxed and unstretched states, and the crossing coil strands being connected to one another by means of a binder at their points of intersection to render the structure cohesive.

12. A non-woven fabric according to claim 10, the two groups of coil strands being mechanically interlocked, by virtue of a contraction of said coil strands of at least one of said groups from a stretched state imparted thereto prior to and during the laying thereof into the coil strands of the other group, to render the structure cohesive.

13. A non-woven fabric according to claim 12, the contracted edge to edge dimensions of the entangled coil strand structure in the direction of stretching being between about 50 and 90% of the axial lengths of the various stretched coil strands oriented in the respective direction.

14. A non-woven fabric according to claim 13, the crossing entangled coil strands further being connected to one another by means of a binder at their points of intersection.

15. The process of making an elastic non-woven fabric with high multi-directional stretchability, comprising the stepsof disposing a first group of resilient and highly extensible coil strands of mono-filamentary nature into a single layer formation, laying a second group of resilient and highly extensible coil strands over one side only of said layer of said first group of coil strands and in crossing relation thereto, compacting said groups of coil strands each into the other from one side only to the form of a structure having the crossing coil strands entangled with each other and having the axes of all coil strands disposed in a single common plane, and treating the assembly of coil strands to render the structure cohesive.

16. The process of claim 15, wherein said groups of coil strands are laid one into the other While in their relaxed and unstretched states, and said treating step comprises interconnecting said entangled crossing coil strands to one another by means of a binder at their points of intersection.

17. The process of claim 15, wherein at least one of said groups of coil strand is in a stretched state while one is being laid and compacted into the other, and said treating step comprises relaxing the stretching forces to permit the stretched coil strands to contract and effect a mechanical interlocking of the crossing coil strands at their points of intersection.

18. The process of claim 17, wherein at least said one group of coil strands is stretched up to about 900% of their relaxed state lengths prior to the compaction operation.

19. The process of claim 17, wherein at least said one group of coil strands is stretched up to about 500% of their relaxed state lengths prior to the compaction opera tion.

20. The process of claim 17, further comprising the step of interconnecting said entangled crossing coil strands to one another by means of a binder at their points of intersection.

21. The process of claim 20, wherein the binder is applied to said coil strands prior to the relaxation of the stretching forces.

22. The process of claim 20, wherein the binder is applied to said coil strands subsequent to the relaxation of the stretching forces.

23. The process of making an elastic non-woven fabric with high multi-directional stretchability, comprising the steps of securing a first plurality of axially stretched resilient and highly extensible coil strands of mono-filamentary nature at their opposite ends each to a respective associated pair of anchoring elements so as to define a first single layer formation, securing a second plurality of axially stretched resilient and highly extensible coil strands of mono-filamentary nature at their opposite ends each to a respective associated pair of anchoring elements and in crossing relation to said first coil strands so as to define a second single layer formation in superposed relation to said first layer formation, pressing said layer formations against one another to compact said pluralities of coil strands into a structure having the crossing coil strands entangled with each other and the axes of all coil strands disposed in a single common plane, and releasing said coil strands from their respective pairs of anchoring elements to permit said structure to contract in all directions so as to cause said coil strands to become mechanically interlocked and render the structure cohesive.

24. The process of claim 23, further comprising the step of treating said coil strands with a binder to supplementarily interconnect the entangled crossing coil strands to one another at their points of intersection.

25. The process of claim 24, wherein the treating step is effected prior to release of said structure from said anchoring elements.

26. The process of claim 24, wherein the treating step is effected subsequent to release of said structure from said anchoring elements.

References Cited UNITED STATES PATENTS 3,449,199 6/1969 Mead 161--47 3,133,852 5/1964 Crane et al 161-47 3,380,484 4/1968 Kraszeski 3X 3,022,063 2/1962 Crane et al. 16147X HAROLD ANSHER, Primary Examiner I. C. GIL, Assistant Examiner US. Cl. X.R. 

